Packaged arrays of inductive coils have extensive use in telephone communication systems wherein there is a need to add inductance to various types of communication circuits. Assemblies of toroidal coils find extensive usage as inductive coils in telephone cable transmission systems wherein the loading coils act to compensate for capacitance between the wire pairs extending to subscribers' stations. Other assemblies of toroidal wound coils find utility as inductor devices used to balance subscriber lines in telephone exchanges.
Loading coil assemblies may vary in size and contain as many as several hundred toroidal wound coils. In order to facilitate assembly, subsequent handling, and installation, it is essential that the assemblies be provided with mounting facilities and structural arrangements that insure ease of manufacture, compactness, and light weight while providing an overall construction that is rugged and that permits complete encapsulation to seal the assembly from the environment.
Numerous diverse arrangements have been devised to package loading coils in an attempt to facilitate assembly and wiring of compact assemblages of individual coils. An example of the prior art may be found in U.S. Pat. No. 2,147,245, which discloses stacks of toroidal coils mounted on dowels and positioned within slit circular metallic tubes so that a number of tubes may be assembled and encapsulated within a metal casing. Further examples of packaged loading coils are disclosed in U.S. Pat. No. 2,692,302, which shows a screened cylinder for receiving stacks of coils; U.S. Pat. No. 2,548,205, which discloses cardboard mounting tubes for receiving stacks of coils; U.S. Pat. No. 3,526,712, which illustrates circular arrays of coils mounted along and about a central post and British Patent No. 366,791, which discloses a number of carrier frames supporting individual coils or coil containers in such a fashion that the carrier frames may be mounted within a protective metallic case.
Recently, the Western Electric Company, Inc. has furnished packaged loading coil assemblies wherein a stack of toroidal coils are mounted on a rod and then a a pair of stacks are assembled into a contoured rectangular-shaped plastic case. These cases, which are generally oval in shape, are further assembled about a core, wrapped with a corrugated liner, tied, placed between plastic cover halves, and finally the assemblage is encapsulated. This loading coil assembly is further shown in a patent application filed in the name of Robert J. Reinebach even date herewith, Ser. No. 864,303.
U.S. Pat. No. 3,964,009 shows a case for housing a choke coil which comprises two hinged circular-shaped pockets, one of which has two enlargements to receive a pair of guide pins about which are laid the coil wires that run through necked extensions of the case to suitable connections.